Enhanced degradation and mineralization of 4-chloro-3-methyl phenol by Zn-CNTs/O3 system

•Zn-CNTs capable of generating H2O2 was prepared and used in Zn-CNTs/O3 system.•Zn-CNTs can effectively reduce oxygen to form H2O2 on their surface.•Zn-CNTs can obviously enhance the mineralization of CMP.•The possible catalytic mechanism was proposed.

A novel zinc-carbon nanotubes (Zn-CNTs) composite was prepared, characterized and used in O3 system for the enhanced degradation and mineralization of chlorinated phenol. The Zn-CNTs was characterized by SEM, BET and XRD, and the degradation of 4-chloro-3-methyl phenol (CMP) in aqueous solution was investigated using Zn-CNTs/O3 system. The experimental results showed that the rate constant of total organic carbon (TOC) removal was 0.29 min−1, much higher than that of only O3 system (0.059 min−1) because Zn-CNTs/O2 system could generate H2O2 in situ, the concentration of H2O2 could reach 156.14 mg/L within 60 min at pH 6.0. The high mineralization ratio of CMP by Zn-CNTs/O3 occurred at wide pH range (3.0-9.0). The increase of Zn-CNTs dosage or gas flow rate contributed to the enhancement of CMP mineralization. The intermediates of CMP degradation were identified and the possible degradation pathway was tentatively proposed.